The present application generally relates to electrical plug and plug receptacle assemblies. More particularly, the present application relates to an electrical plug and plug receptacle assembly having an interlock mechanism that prevents a switch from being turned on unless a plug is positioned in the receptacle and prevents the plug from being removed from the receptacle when the switch is turned to an ON position. The electrical plug and receptacle assembly with an interlock mechanism is useful in hazardous locations, such as National Electric Code (NEC) Class I, Division 1 areas, and may advantageously be used in explosion-proof electrical plug receptacles.
In hazardous locations, such as NEC Class I, Division 1 areas, electrical plugs and receptacles are required to supply electric power to various pieces of equipment and/or machines. Safety is of the utmost importance in such locations due to the presence of high voltage and the presence of combustible material. As a result, it is desirable to provide safety features that prevent a switch within an electrical plug receptacle from being energized unless the electrical plug is positioned in the receptacle, and that prevent the electrical plug from being removed from the electrical plug receptacle when the switch is energized.
In a prior design, a flaw existed such that the switch could be positioned between the ON and OFF positions, wherein the electrical plug could be removed without de-energizing the switch, and the switch could be energized without full engagement of the plug. Therefore, it would also be desirable to provide a switch that is more reliably positioned in either the ON or OFF position.